1. Field of the Invention
The present invention relates to an engine positioning structure for a rear wheel drive automobile, the automobile having a passenger compartment and an engine compartment in front of the passenger compartment, the two compartments being separated by a dash panel, with an engine mounted in the engine compartment driving the rear wheels.
The present invention also relates to the above-described engine positioning structure having a certain power train engine positioning structure.
2. Description of Prior Art
An example of the prior art engine positioning structure for a rear-wheel drive automobile is described in Japanese Patent Unexamined Publication No. 6-239147.
Namely, as shown in FIG. 6, typical structure for FR (Front engine and Rear-wheel drive) type has passenger compartment 61 and engine compartment 63 in front of passenger compartment 61 separated by dash panel 62, such that engine 64 mounted vertically in engine compartment 63 drives rear wheels (not shown). In this connection, in the figure, 65 is a front side frame, 66 is an intercooler, 67 is a cooler condenser, and 68 is a radiator.
In this prior art structure, since the engine as a heavy load is disposed far forward from the center of the automobile in the engine compartment, there is a problem that Yaw moment of inertia becomes relatively large.
In order to reduce this Yaw moment of inertia and improve steering stability, Japanese Patent Unexamined Publication No. 2001-105833 discloses to make an air conditioning unit compact, and Japanese Patent Unexamined Publication No. 10-324141 discloses to use an air conditioning unit of film dumper key type.
By using such air conditioning units, it may be possible to retreat the engine of front-engine type to the center of the automobile, reduce the Yaw moment of inertia, and thus to improve the steering stability to a certain extent.
In order to reduce the Yaw moment of inertia more and thus improve the steering stability further, it is necessary to make the engine smaller or to employ engine layout in which the engine has more retreated position. However, since the engine cannot be made smaller unlimitedly, it is required to retreat the engine more toward the center of the automobile.
However, mere retreat of the engine creates a problem of interference between the engine and a dash panel which separates the engine compartment from the passenger compartment.
Another example of the prior art engine positioning structure for an automobile is shown in FIGS. 39 and 40.
FIG. 39 is a plan view showing a prior art engine positioning structure. FIG. 40 is a cross-sectional view of XXXX—XXXX arrows line in FIG. 39. Referring to these figures, an engine positioning structure has a passenger compartment 281 and an engine compartment 283 in front of the passenger compartment 281, the two compartments being separated by a dash lower panel 282, with an engine 284 mounted in the engine compartment 283 driving the rear wheels.
A transmission 285 is connected to the engine 284. A propeller shaft 287 is connected to an output axis 286 of the transmission by way of a universal joint. Thus, the engine 284 mounted in the engine compartment 283 drives the rear wheels.
In addition, an exhaust pipe 288 is connected to the engine 284, and this exhaust pipe 288 extends rearwardly. A catalyst 289 for cleaning an exhaust gas is connected to the extending part of the exhaust pipe 288. This catalyst 289 is positioned exterior of the automobile relative to tunnel part 291 defined at the center of floor panel 290. In this regard, when the catalyst 289 positioned exterior of the automobile relative to tunnel part 291 is mounted at a side of transmission 285 as shown in FIG. 40, it is necessary to provide a protruded part 291a to the tunnel part 291. As a result, the passenger compartment is narrowed in that amount.
Furthermore, since the reaction rate of the catalyst 289 depends on the temperature, it is required to position the catalyst as close to the engine 284 as possible. On the other hand, if the catalyst 289 is disposed at the position corresponding to the footing of the passenger as shown in FIGS. 39 and 40, that part corresponding to the footing of the passenger is heated by the exothermal reaction of the catalyst 289. In order to prevent the harm caused by the heat, it is necessary to use an insulator at a great cost.
On the other hand, as described above, considering the Yaw moment of inertia and the steering stability, it is required to retreat the engine 284 as a heavy load more toward the center of the automobile. However, mere retreat of the engine 284 creates a problem of interference between the engine 284 and a dash lower panel 282 which separates the engine compartment 283 from the passenger compartment 281.
In this connection, in FIGS. 39 and 40, 292 represents a front wheel, 293 represents a front side frame, 294 represents a lower arm of a front suspension, 295 represents a power steering, 296 represents a radiator, 297 represents a side sill, 298 represents a floor frame, and 299 represents a front seat.
Meanwhile, Japanese Patent Unexamined Publication No. 7-285347 discloses to mount an engine vertically within an engine compartment, and to position the catalyst exterior of the automobile relative to tunnel part. However, since the structure disclosed in this article is substantially the same as the one shown in FIGS. 39 and 40, it also has the above-described problem.